Formulae and Molecular Models

Figure 14.2 The fully displayed (or structural) formulae and molecular models of the first six alkanes.

Fluorescein structural formula and molecular model. This strongly fluorescent dye has many applications. It is widely used to study retinal circulation and various diseases involving the retina. The technique is known as fluoi escein angiography. Fluorescein can be bound to DNA and other proteins and its fluorescence used as a probe of these molecules and their interactions. Fluorescein is also used for water tracing to provide information on the contamination of underground wells. In addition, it has been used as a laser dye. 

Figure 17-12 Structural formula and molecular model of Calmagite. Note the similarity to Eriochrome Black T (see Figure 17-11).

Figure 2.12 Molecular and structural formulas and molecular models of four common molecules.

The simplest type of organic compounds is the hydrocarbons, which contain only carbon and hydrogen atoms. The hydrocarbons are used as fuels for domestic and industrial heating, for generating electricity and powering internal combustion engines, and as starting materials for the chemical industry. One class of hydrocarbons is called the Table 2.8 shows the names, formulas, and molecular models of the first... 

Lewis formula and molecular model of phosphorus oxychloride molecule... 

Chemists in the seventeenth century discovered that the substance that gives red ants their irritating bite is an acid with the formula HCHO2. They called this substance formic acid after the ant, whose Latin name is formica rufus. Formic acid has the following structural formula and molecular model ... 

We can also represent molecules with structural formulas. The structural formula shows not only the elemental composition, but also the general arrangement of atoms within the molecule. In the case of water, each of the hydrogen atoms is connected to the oxygen atom. Figure 2.13 shows the molecular formula, structural formula, and molecular models (both ball-and-stick and spacefilling variety) for water. Note that the chemical bond between two atoms can be represented with either a pair of dots or a line. 

Representing Compounds Chemical Formulas and Molecular Models 90... 

The definitive structures of the a- and (3-dextrins were shown by French and Rundle [9] to be composed of six and seven D-glucose residues, each linked a-1 4 in a cyclic structure, respectively. Freudenberg and Cramer [10] and French, et al. [11] showed that 7-dextrin had eight D-glucose residues. Figures 8.1 and 8.2 show the structural formulas and molecular models of these cyclic dex-... 

Figure 1.6 Perspective Structural Formulas and Molecular Models...

The constitutional formula and molecular weight of cellulose determined on the basis of chemical and physico-chemical experiments has been confirmed by X-ray analysis, which has also led to the discovery of the microcrystalline structure of cellulose. Today the structural model proposed by Meyer and Mark [21] and Mark and Misch [22] based on the X-ray measurements of Polanyi [23] and Sponsler and Dore [24] and taking into consideration Haworth s conclusions about the existence... 

Lukovits, I. (1995a). A Formula for the Hyper-Wiener Index. In QSAR and Molecular Modelling Cocepts, Computational Tools and Biological Applications (Sanz, F., Giraldo, J. and Man-aut, F., eds.), Prous Science, Barcelona (Spain), pp. 53-54. 

The following two examples deal with writing molecular formulas from molecular models and writing empirical formnlas from molecular formulas. 

Calculating the formula weight from a formula or molecular model Given the formula of a compound and a table of atomic weights, calculate the formula weight. (EXAMPLES 3.1,3.2)... 

In the chemistry classroom, the teacher can provide the students with the names and molecular formula (columns 1 2 in Table 1) and ask them to use the CMM software for drawing structural formula, ball-and-stick, and 3D models (columns 3, 4 5 in Table 1) for each one of the compounds. Another option is to submit a similar table with blanks (empty cells) in various rows and columns and ask the students to fill the missing cells. For example, give the molecular formula and 3D model of propanoic acid but leave blanks in the columns of compound name, structural formula, and ball-and-stick model. 

Give the name, condensed structural formula, and molecular mass of the molecule whose ball-and-stick model is shown. Refer to the color scheme in Figure 3-3. 

Molecules are usually represented as 2D formulas or 3D molecular models. WhOe the 3D coordinates of atoms in a molecule are sufficient to describe the spatial arrangement of atoms, they exhibit two major disadvantages as molecular descriptors they depend on the size of a molecule and they do not describe additional properties (e.g., atomic properties). The first feature is most important for computational analysis of data. Even a simple statistical function, e.g., a correlation, requires the information to be represented in equally sized vectors of a fixed dimension. The solution to this problem is a mathematical transformation of the Cartesian coordinates of a molecule into a vector of fixed length. The second point can... 

Write structural formulas or build molecular models and give the... 

Write structural formulas or build molecular models and give the functional class and substitutive names of all the isomeric alcohols that have the molecular formula C4H10O... 

Wnte structural formulas or build molecular models for all the constitutionally isomenc alcohols of molecular formula C5H12O Assign a substitutive and a functional class name to each one and specify whether it is a pnmary secondary or tertiary alcohol... 

Wnte a structural formula or build a molecular model and give a correct lUPAC name for each alkene of molecular formula C7H14 that has a tetrasubstituted double bond... 

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